Multiple potentiometer



Sept. 7, 1943. c, B. MOORE MULTIPLE POTENTIOMETER Filed Aug. 13, 1938 '7Sheets-Sheet l INVENTOR. COLEMAN B. MOORE .4 TTORNEY P 1943-v c. B.Mocha 2,328,664

lULTI-PLE POTENTIOHETER Filed Aug. 13, 1938 7 Sheets-Sheet 2 mmvmnCOLEMAN a some AT ORNLY Sept. 7, 1943. r c. B. MQORE MULTIPLE POTENTIOMETER 7 Sheet-Sheet 3 Filed Aug. 13, 1958 INVEN TOR. COLEMAN B. MOOREWLW ATTORNEY 5 v wm P 7, 1943. c. B. MOORE 2,328,664

MULTIPLE POTENTIOMETER 7 Filed Aug. 1:5, 1958 'r Sheets-Sheet 4 F|G.l2.5 H65 INVEN TOR.

COLEMAN a MOORE A TTORNEY Sept. 7, 1943. c. B. MOORE MULTIPLEPOTENTIOMETEB Filed Aug. 15, 1958 7 Sheets-Sheet 5 INVEN TOR.

n N m T T. A

Sept. 7, 1943.

C. B. MOORE MULTIPLE POTENTIOMETER Filed Aug. 13, 1938 7 Sheets-Sheet 6INVEN TOR.

COLEMAN B. MOORE Y ATTORNEY P 7, 1943. c. B. MOORE MULTIPLEPOTENTIOMETER Filed Aug. 15, 1938 7 Sheets-Sheet v FIG. n

IN V EN TOR.

ATTORNEY E R O O M B N A M E L O C Faiented Sept. 7, 1943 MULTIPLEPOTENTIOMETER Coleman B. Moore, Carroll Park, Pa., assignor to The BrownInstrument Company,

Philadelphia;

Pin, a corporation of Pennsylvania Application August 13, 1938, SerialNo. 224,826

9 Claims.

The present invention relates to a recording potentiometer. In mostinstruments of this type, th value of the temperature at a series ofpoints is measured sequentially, and a mark is made on a properlycalibrated chart by a pen of some sort to indicate the varioustemperatures. Previous to my invention it was customary to use amultiple colored ribbon that was moved to various positions inaccordance with the place that was having its temperature measured. Ahammer member, moved to a position along the chart according to thetemperature, was then brought into contact with the ribbon to press itagainst the chart to make a mark thereon. This method has the seriousobjection of limiting the number of records that can be made by a singleinstrument to the number of colors that it is feasible to place on asingle ribbon, usually three or four.

My. invention obviates the above'limitation to the number of recordsthat can be made by a single potentiometer instrument and, permits fouror five times as many records per instrument to be made. I use a printwheel that is indexed for each measurement to bring a suitable characterinto printing relation with the chart, which print wheel is then movedto a position along the chart corresponding to the temperature beingmeasured and pressed there against. Ii desired, each of the characterscan be made different in form and a single colored ink may be used, or,if desired, each character can be printed in a different colored ink.

In recording temperatures with an instrument description I will disclosea printing mechanism that has a fixed time between each of the recordsand a printing mechanism that has a variable time between each of therecords, said variable time depending in each case upon the differencein the value of the two temperaturesto be recorded.

The various features of novelty which characterize my invention arepointed out with particularity in theclaims annexed to and forming apart of this specification. For a better understanding of the invention,however, its advantages and specific objects obtained with its use,

of this type, there is of necessity'an interval of time between the timeone record is made and, the time the next is made, during which themeasuring mechanism is setting the print-wheel at the correct positionalong the chart. If the diiference between the values of the varioustemperatures is about the same, the interval between the recordings willbe about the same, and the instrument can be adjusted to print at equalintervals of time. If, however, the difference between the values of thevarious temperatures varies greatly and the instrument records at equalperiods of time, there will be an unnecessarily reference should be hadto the accompanying drawings and descriptive matter in which I haveillustrated and described a preferred embodiment of the invention.

In thedrawings: Fig. 1 is a perspectiveview of a potentiometer; Fig. 2is a side view of the printing mechanism;

Fig. 3 is a view looking from the left of Fig. 2 on line 3-3;

Fig. 4 is a view taken on line l-4 of Fig. 3; Fig. 5 is a side view ofthe actuating mechanism for my printing mechanism;

Fig. 6 is a view looking from the left of Fig. 5; i

Fig. '7 is a front view of a potentiometer incorporating the. printingmechanism of the presfor the'indexing mechanism;

large lapse of time between the time that the measuring mechanism comesinto balance and the time that the record is made where, the differencebetween the temperature values issmall. For records of this type, it isdesirable to have a variable time between the printing of one record andthe printing of the next, the time depending upon how long it takes themeasuring mechanism toreach balance. In the following granted March 14,1939, on'an application filed and Ernest Kessler.

Figs. 14 and 15 are views of a modified form of ink pad;

Fig, 16 is a view of a printing mechanism control that has a variabletime between each record; and

Fig. 17 is a view of another embodiment ofa variable time printingmechanism control.

. In the form illustrated in Figs. 1 to 3, their;-

vention is incorporated in a potentiometer recording instrument of thecommercial type, known as the Brown Potentiometer, and of the particularform disclosed in Patent 2,150,502,

jointly by Thomas R. Harrison, Ernest H. Grauel The said instrumentcomprises a gaivonometer, having a pointer 2 which deflects in responseto a condition of unbalance in a potentiometer measuring circuit. Theinstrument also comprises mechanical relay provisions including aconstantly rotating power shaft I2, and controlled by the galvanometerpointer 2 deflection from its normal position, for periodicallyrebalancing the potentiometer circuit, and for moving a recordercarriage '23 along a travellingrecord strip 26 as required to make arecord on said strip of the varying value of the quantity measured.

The mechanism of Fig 1, through which the deflection of the galvanometerpointer 2 controls the adjustments of the recorder carriage 23 and therebalancing of the potentiometer circuit 'on a variation in the value ofthe quantity measured by the galvanometer, comprises a pointer positiongauging element 3. The latter is pivotally supported, and in connectionwith the hereinafter mentioned shaft 6, has a bias which may well be duepartly to spring and partly to gravitational action, to turn upward intothe position in which one or another of the shoulders 5 of the member 3,engages the pointer 2. The element 3 is engaged by, and turns with thearm 6' of a rock shaft 6. A spring I0, Figs. 1 and 16, tends to hold arocker 8 which is journalled on a pivot 9, in the position in which therocker engages the lateral projection 'I' of an arm I secured to theshaft 6, and thereby holds the latter in a position in which theshoulders 5 are all below the pointer 2.

A cam II which is carried by the constantly rotating power shaft I2,turns the rocker 8 about its pivot against the action of the spring I0,once during each revolution of the shaft. This allows the arm I to turncounter-clockwise, as seen in Fig. 1, until the corresponding angularmovement of the shaft 5 is interrupted by the engagement of one oranother of the shoulders 5 of the member 3 with the galvanometer pointer2. The shoulders 5 are so arranged that the turning movement of theshaft 6 and arm 'I thus permitted, will be greater or less, according tothe defleotive position ofthe pointer 2 at the time. When the arm I thusturns counter-clockwise, itslateral projection I engages and turns asecondary pointer element I4 into a position corresponding to the thendeflection of thepointer 2. The secondary pointer I4 is looselyjournalled on the shaft 6, and has a gravitational bias to turn in theclockwise direction as seen in Fig. 1, so that the arm I4 normal y bearsagainst the projection I' of the arm 1.

At the end of each angular adjustment of the secondary pointer I4 into aposition corresponding to the then deflection of the galvanometer 2, oneor another of high, neutral and low steps or shoulders along the edge I5of a locking member I5, engages the bottom wall of a slot I4 in themember I4 and thereby frictionally holds the latter in the positionoccupied by it when such engagement occurs. The locking part I5 is givena tendency to move into locking engagement with the secondary pointer Il by the spring I0, but is periodically held out of such engagement bythe action on a. lateral projection form the member I5 of a projectionISA carried by a ratchet lever I6 pivoted at IGB.

The lever I6 has a spring bias to turn forward, in the clockwisedirection as seen in Fig. 1, but throughout the major portion of eachrotation of the shaft I2, the lever I6 is held in a retracted positionby a cam I! carried by said shaft and engaged by the cam follower rollIGD carried tion.

by the lever IS. The ratchet lever I6 is operatively connected to twopawls I6E and IGF cooperating with a toothed wheel l8. Each of saidpawls is biased for movement into a position in which it does not engagethe teeth of the wheel I8, but one or the other of'the pawls is broughtinto engagement with the teeth of the wheel I8, on each forward orclockwise movement of the lever I6, by the locking part I5, if thelatter is then at one side or the other of its intermediate or neutralposition, occupied when the galvanometer pointer 2 is in its neutralposition.

The position assumed'by the part I5 when in locking engagement with thesecondary pointer I4, controls the action of the pawls IGE and IBF byvirtue of the fact that the part I5 carries a pawl engaging spring armI5". The movement of the locking part I5 into the position in which itshigh shoulder of its edge I5 engages the secondary pointer I 4, causesthe arm I5 to move the pawl IBE into operative engagement with the teethof the ratchet wheel IB, and the clockwise or forward movement of theratchet lever I6 then gives a clockwise adjustment to the ratchet wheel.Conversely, when the part I5 moves into the position in which its lowshoulder of edge I5 engages the secondary pointer H, the arm I5" shiftsthe pawl I BF into operative engagement with the wheel I8, and thelatter is then adjusted in the counter-clockwise direction.

The extent of the adjustment then given the wheel I8 is made dependentupon the position of the secondary pointer I 4, as said positiondetermines which of the various shoulders of an arm IGG carried by thelever IE shall then engage a projecting portion I4" of the secondarypointer I4 and thereby arrest the forward movement of the ratchet leverI6, after an extent of forward movement varying with the shoulderengaged. In the neutral position of the galvanometer pointer andsecondary pointer I4, the projection Id" of the latter engages thecentral shoulder IGG' or the arm IBG and the lever I6 is then heldagainst any operative movement in the clockwise direc When the secondarypointer position is more or less to one side or the other of its neutralpositions, the portion I 4" engages an upper or lower shoulder of arm I6G more or less distant from the central shoulder IBG', and the lever I6is then permitted more or less forward movement.

The rotation of the wheel I8 in one direction or the other, effectscorresponding potentiometer rebalancing adjustments, and correspondingposition "adjustments of the recorder carrierindicated generally at 23.The rebalancingadjustments are effected by means of a rheostat shaft I9which is geared to the shaft I8 on which the wheel I8 is secured. Therotation of the shaft I9 moves a bridging contact 20 along theconvolutions 2| of a potentiometer slide resistance helically disposedabout the axis of the shaft I9, and thereby varies the amount ofisaidlre'sistance in the potentiometer circuit. The resistanceadjustments made in response tox a 'deilection of the galvanometerpointer in either'direction away from its neutral position rebalances,or tends to rebalance, the potentiometer circuit and thereby returns, ortends to return, the galvanometer pointer to its neutral position.

- The rotation of the wheel I8 adjusts the recorder carrier 23 by virtueof the fact that the teeth of the wheel I8 are in mesh with the teeth ofa gear carried by a carriage adjusting shaft 22. The latter is formedwith a. thread groove 22' of coarse pitch. which receives a cam ormutifeeding or advancing movements'by a record feed roll 21. The latteris intermittently rotated by means of a worm and screw connectionbetween the shaft of the roll 21 and a transverse shaft 23,

and connection including a ratchet and lever (not journaled for rotationin movements impart placement movements whose forward end is shown)between the shafts 23 and I2.

The measuring apparatus Just described is mounted in a casing 23 (Fig.7) and issupported therein by two side plates, 30 and 3|, in such amanner that it may be swung out of the casing 23, when the door thereofis opened, for inspection. The carriage adiustingishaft 22 along with acarriage supporting and rotating shaft 32 are the side plates and theirthe proper indexing and disto the print wheel mechanism indicatedgenerally at 23., r

Referring more particularly to Figures 2 to 4, the details of theprinting'mechanism will now be described. This printing mechanismconsists essentially of three parts, a supporting part for the entiremechanism to keep it correctly positioned, a moving part to shift itlongitudinally, and a tilting part upon which the printing and inkingwheels are mounted and with which they are moved into engagement withthe chart in order to record the .values being measured. The supportingpart comprises a journal 33 that is slidable along shaft 32 and hasteeth thereon to engage the splines on said shaft so that it may berotated as the shaft is indexed. Mounted on this journal is a generallyU-shaped-member34 bent at right angles to the side of the instrument andcarries a roller 35 adapted to ride on one edge of a channel member 33-fastened across the front of the instrument between side plates 30 and3|. Attached to the inturned end, and extending below and then up infront of the channel member 36, is a pointer 31 that cooperates with ascale 38 attached to the channel member to indicate the position of the'carriage and, therefore, the temperature of the condition beingmeasured.

The moving part of the print mechanism consists of a journal 33 formedwith a tooth therein that surrounds shaft 22. The tooth enters the vnal33 therealong, and

helical thread 22' on the shaft so that any rotation of the shaft willmove the journal therealong. Formed integral with an extending abovejournal 39 is atubular member 40 in the bore of which is inserted aspring 4| and a pin 42, having an enlarged head on its lower end. Thespring forces the head of pin 42 into frictional engagement with shaft22 and serves to prevent overtravel of cross-part of member 45 has aroller 53 attached to it that extends into the groove of a channelmember I6 for a purpose to be later described. The washer 46 permits,however, relative turning movement between parts 34 and- 45. Extendingfrom the inner face of member 45 are three stud shafts 41, it and 49that have mounted for rotation on them, respectively, gears 5| and 52.

Gears 5% and El mesh with and are driven by a gear 53 that is rigidly atached to the journal 33, while gear 52 is driven by gear 5! to rotateina direction opposite to gear 50. Gear has a journal "formed thezewithupon which is mounted a print wheel 54 that has raised portions 55 onthe surface thereof formed in the shape of the characters it is desiredto print. The print wheel also-has to the right of its portions 55 acollar upon which are printed characters corresponding to those at 55,but offset thereto in such a manner that when the character to beprinted is at the bottom of the wheel, a similar character will appearat the front of the wheel on collar 56 and opposite pointer 55A. Thiprint wheel is held in place on its journal by a thumb knob 51.

A journal is also formed on gear 52, and mounted upon it is an ink padsupporting member 53 whose surface is formed with a series of circulargrooves in which are placed ink pads.

the pen carriage. A washer 43 isprovided on the upper end of pin. 42 tolimit its downward movement. Formed on the side of the tubular member isan arm that is attached by a screw, or other meansQto the side of member34. The effect is that rotation of shaft 22 will move jourby means ofarm 44, the

member 34 will be moved the same amount.

The tilting part comprises a member 45 having its lower end bent toU-shape to provide two bearings for it on journal 33, around which itmoves, inside of the arms of member 34 as shown in Fig. 3. A springwasher 46 is inserted between the right-hand sides of members 34 and 45to prevent lateral play therebe'tween, so that as member 34 is shifted,as above describedmember 45 will retain a definite relation thereto. The

. shaft 66 that extends between side These ink pads each consist of acup-shaped lation, a piece of felt 6| that has been saturated with thedesired colored ink. Fingers 62 extend from the side of member 58 andover the ink pads to hold them in place on the wheel, and the entireassembly is held on its journal by a thumb screw 53.

As many characters 55'and ink pad 6| are provided as there are recordsto b printed in accordance with the measurement to be made by theinstrument. When anew measurement is to betaken, the shaft 32 is indexedin a manner to be, described, and this in turn rotates gears 50, 5i and52 tobring a character 55 into printing position over the chart 26,. Asthis occurs, another character is brought into engagement with its inkpad to place a supply of ink thereon. A A spring washer 52A is placedbetween gear 52 and member 45 to act to retard movement of that gear andprevent any possibility of overtravel. The manner of indexing shaft 32and of making an impression on the chart will now be described. I

When a new measurement is to be made by the instrument, the galvanometeris switched into circuit with a thermocouple that is located at thepoint where the measurement is to be taken.

Since'the value of the new measurement may determined number of cyclesis made between each indexing and printing operation. To this end, lever8, which is oscillated once by cam H for each cycle of the instrument,has a link pivoted thereto, tached to a plate on a journal 69, which in65 that is mounted to oscillate turn moves around plates 3| and 32 tosupport the chart roller 2'l.- Oscillation of plate '65 around shaft 66rotates, by means of a pawl 51 attached to the plate, a ratchet wheelthe other end of which is atshaft 88. A second pawl "A preventsretrograde movement of'ratchet 88. The ratchet 88 and journal 89,therefore, make one complete rotation for a predetermined number ofcycles of the instrument, which number of cycles can be altered bymoving the right end of link 84 nearer to or farther from the axis oflever 8.

A pair of cams 10 and H are fastened together and attached to journal 89for rotation therewith. The cam 78 serves to determine the printingmovements of the characters 55, while cam l l serves to lock theindexing mechanism in place. A pin extending between the two camsactuates the indexing mechanism. Bearing on the surface of cam I8 i aroller I2 that i mounted on an off-set end of a lever-l4, whichoscillates around the splined shaft 32 and is biased in acounter-clockwise direction by a spring 15. The rear end of lever 14 isattached to a channel member 16, to the other end of which is attached alever (not shown) also oscillatable around shaft 82 and similar to theback half of lever 14. As th cut-out portion "A of cam 10 comes under anedge 18 of lever 14, this lever turns counter-clockwise under the biasof spring 15 to move the'cha-nnel member 18 upwardly. Since roller 58 onmember 45, carrying the print wheel 54 andink pad wheel '58, is in thechannel of member 15, this roller '58 will be lifted upwardly, andmember 45 will be pivoted around the journal 88 to move a character 55into contact with the chart to make an impression thereon. It will beseen that the leading edge of cut-out portion 18A is abrupt, so thatwhen it comes under edge 73, that edge will move down very quickly tomake a sharp impression on the chart, while the following edge of thecutout portion 18A will act on roller 12 to move lever 14 clockwise tolower channel member I8 and raise the character 55 from the chart.

Immediately after the printing has taken place, the instrument isindexed to place another measuring element, such as a thermocouple, inthe galvanometer circuit. The indexing is accomplished by a pin 1! thatextends between the two cams 78 and 1| and is attached thereto. Onceduring each revolution of the cams, the pin 11 engages a tooth on thperiphery of toothed wheel 78 and rotates it the distance of one tooth.Normally this wheel 18 i locked in position by a lever 19, pivoted at 88and having 88 that has a journal 58 thereon surrounding as cut-outportion "A of cam 18 comes under a finger on its lower end engaging thetoothed wheel while a roller 8| on its upper end bears on the surface ofcam 1|. The cycle of the instrument after the printing brings a cut-outportion HA of cam 1| under the roller 8|. At the same time, pin 11engages a tooth on wheel 18 to rotate it; thus lever 18 is movedcounterclockwise with roller 8| moving into the cutout portion HA. Thenext cycle of the instrument again brings the high portion of cam 1|under roller 8| and thereby moves the finger on the lower end of lever19 into the spa e tween two teeth of wheel 18 to lock it in place.

Shaft '82, upon which the wheel 18 is mounted, extends through both sideplates 8| and 88, and when it is rotated, through gearing 84, rotates ashaft, 85 in a switch (which may be of the type shown in Harrison Patent1,770,918) to connect another thermocouple in circuit with thegalvanometer. Rotation of this shaft also, through gearing 86, rotatesthe splined shaft 82 to move another character into printing position,ready .be made on chart 2G,

for the next impression to edge 18. The upper gear of the gearing 88which extends over splined shaft 82 has a square hub 81 (Fig. 8) throughwhich are threaded two set screws 88. By adjusting thes screws relativeto thehub 81. shaft 82 can be rotated a slight amount to insure anaccurate setting of the characters 55 in their printing position inorder to get a clear-cut impression.

The operation of the device should be apparent from the above-detaileddescription, but a short rsum will now be given. Starting with the partsin the positions they assume after an indexing operation has beenperformed, the subsequent cycles of the instrument will balance thegalvanometer and thereby rotate shaft 22 to shift the printing mechanismto its proper position above the chart. The balancing operations willalso rotate cams 18 and H through the pawl and ratchet mechanism 87, 88by movement of the lever 8. When the cut-out portion 18A of cam 18 movesunder edge 13, the channel member 18 will be lifted under the bias ofspring 15 to move a character 55 into engagement with the chart. Thesame cycle of the instrument that permits printing will also move thefollowing edge of cut-out portion "A under roller 12 to lift thecharacter 55 from the chart, thus making a clear-cut impression. Thenext cycle of the instrument will bring the portion HA of cam II underroller so that pin 11 can move toothed wheel I8. As this wheel rotates,its shaft 82 will adjust the shaft 85 to connect the instrument to'another thermocouple and will also rotate shaft 82 to bring anothercharacter 55 into printing position.

As shown in Fig. 5 of the drawings wheel 18 has twelve teeth, and thereis one pin 11 in between the cams 18 and H. Therefore, the wheel 18 ismoved one-twelfth of a revolution of each indexing movement. With thisarrangement, a thermocouple switch for twelve thermocouples is used, anda print wheel with twelve characters is used, so that the instrument canmake twelve different records. It will be obvious that by varying thenumber of teeth on wheel 18 and the number of pins 1! between the camsl0 and H, that the wheel 18 can be rotated in almost any desired numberof steps. If a different thermocouple is connected to the instrument foreach of the steps, as above described, the instrument can be used toconsecutively measure and record the value of the temperatures to whicheach of these thermocouples is subjected. It is, of course, necessarythat a print wheel be supplied having the same number of printingcharacters that there are thermocouples.

As shown in Fig. 3, each of. the characters 55 on the print wheel 54consists of a numeral to indicate the number of the record being madewith a plus mark in front of it. This plus mark serves a very definitefunction, inasmuch as the balancmg mechanism of the instrument isdesigned to move the print wheel to a position where the vertical lineof the plus mark is exactly over the corresponding temperature line onthe chart. As the printing is done, the horizontal line of the plus markis exactly over the time line on the chart. Thus the numeral indicatesthe number of the record being made, and the point at which the verticaland horizontal lines of the plus mark fall indicates the exacttemperature of the condition being measured and the exact time that itwas made. Any similar characters performing the ;ame function may beused, or, if desired, the iumerals could be omitted and differentcolored nks used to indicate the different records.

The modification of the invention disclosed in Figures 9-12 differs fromthat already described .n several features of construction, includingthe manner of indexing the mechanism and the manner in which animpression is made on a chart. The same reference numerals will be usedfor duplicate parts in the description of this modification. In thismodification, an extension of shaft- I2 has a pinion 90 on its end whichmeshes with a large gear 9| mounted for rotation on a stud shaft 92. Thegear 9I has ahub extension 93 which is, for example, hexagonal in shapeand has slidably mounted on it a journal carrying a gear 94. A spring clip 95 surrounds the journal of gear 94 and resiliently presses a ballinto one of a series of grooves on the-hub 93 of the gear 9I. In thismanner, gear 94 can be adjusted axially of hub 93 by means of disc 96 tobring the gear 94 into mesh with any one of gears 91, 98 or 99 that aremounted on stud shafts and are spaced various distances from the sideplate 3| as shown best in Fig. 11. Each of the gears 91, 98 and 99 is atall times in mesh with gears I00, IN and I02, respectively, that are ofdifferent diameters and are attached to a hub I03 mounted for rotationon a stud shaft I04 extending from side plate 3|. The effect is that thehub I03 will be driven from main drive shaft I2 at varying speeds,depending upon which of the gears 91, 98 or 99 the gear 94 is in meshwith. j

Also mounted on hub I03 are two control discs I05 and I06 that each havea periphery of two radii and that have retaining members I01 and I08,respectively, attached thereto. 'Spacer member I09 is attached to discI06 and is shaped to receive a spanner wrench so that the disc I06 andmember I08 can be rotated relative to disc I05 and member I01 for apurpose to be described. The end of hub I09 has a spring washer I I onit .0 press the discs I and I06 together and thereby prevent anyaccidental relative movement of the two. Each of the discs I05 and I06has a series of notches extending radially from its circumference, andeach ofvthe retaining members has its circumference formed as a seriesof fingers over-lying the notches, as is best shown in Fig. 9. By movingthe discs relative to each other, a variable number of the notches ineach disc can be made to line up with each other, and a cam with avariable are of low portion is formed by the two discs when takentogether. Pins III are then inserted in the aligned notches of the discsI05 and I06, to form in effect gear teeth, and are held in place by thefingers on retaining members I01 and I08. By relatively moving discs I05and I06 and inserting the pins III, there is obtained a mutilated gearhaving a predetermined number of teeth with respect to the length of thearc of the low portion of the cam. As shown in Fig. 9, there are threepins III forming a gear with three teeth, and the low portion of the camis approximately 45.

Rotation of the above described mutilated gear wheel'is used to indexthe printing mechanism and to move the shaft 85 of the thermocoupleswitch to connect another thermocouple in circuit with the galvanometer.This is accomplished by having a toothed wheel II2, of different shapefrom wheel 18, mounted on shaft 82 to be rotated by pins III of theabove-described mechanism. This toothed wheel is also looked in place,as

was wheel 18, except during the time that an indexing operation istaking place. The locking is accomplished by a lever H3 that is pivotedat H4 and has a wide roller II5 on its upper end bearing on theperiphery of discs I05 and I06 and a finger on its lower end extendingbetween two R tation is imparted to the cam II teeth of wheel H2. Thediscs I05 and I05 are being rotated at a constant speed from main shaftI2 of the instrument to periodically bring pins I I I into meshwithwwheel I I2 and perform an indexing operation. The frequency of thisoperation depends upon which of the gears 91, 98, or 99 the gear 94 isin mesh with, and the amount of rotation of shaft 82 depends upon thenumber of pins I I I that is being used.

Rotation of shaft 82 in this modification, as in that of Fig. 1, rotatesa shaft that brings different characters into printing relation with thechart. In this case, instead of usinga splined shaft, there is mountedin the side plates a square shaft H5 that has its ends reduced andjournaled in bearing members IIB which rotate therewith. Slidablyjournaled on shaft H5 is the supporting mechanism for the print carriagethat is now to be described.

The supporting part of this modification of the print wheel mechanismcomprises a journal II1 having a square opening therethrough that isslidable on shaft I I5 and has a circular exterior. Attached to thisjournal is a gear I I8, and rotatably mounted on its ends are backwardlyextending wings II9 of a generally U-shaped supporting member I20 whosefront ends are formed with notches I2 I. Rotatably mounted in the memberI20 is a small idler pinion 5I and a shaft 49 upon which is fastened agear 52, the pinion and gear meshing with and driven by gear I I8 as thesquare shaft II5 is rotated. A wheel for supporting ink pads similar tothose shown in Figs. 2 and 3 is placedon shaft 49 to rotate therewith.

The moving part of the printing mechanism consists of a U-shaped memberI25 whose rearwardly extending ends surround the shaft 22 and whosefront ends form, with pointer 31, a guide that is received by thechannel member 36. The

sides of this member I25 lie close to and outside of the sides ofsupporting member I20, so that as member I25 is shifted along shaft22,the member I20 will be carried therewith to be properly positionedover the chart in accordance with the value being measured. The memberI25 is provided with a cap I25 to cover and protect the inkingmechanism, and is shifted upon rotation of shaft 22 by a spring I21Aformed thereon, extending into groove 22' of the shaft 22.

The print wheel 54 and gear 50 which rotates it are slidably androtatably mounted on a shaft I21, that is in turn mounted to rotatearound the square shaft H5. Attached to each end of shaft I21 is an armI28 having two spring finger extensions I29 that are received in groovesof bushings I30 which surround the bearin members H6. The print wheeland its gear are received between the sides of member I20, and shaft I21is received in slots I2I of said member. In this manner, the frameformed by shaft I21 and its arms I28 may be raised and lowered aroundits shaft Hi to raise and lower the print wheel and frame I20 whichcarries the ink pads '5I. A means to raise and lower the shaft in orderto move a character 55 against the chart 29 consists of a roller IQI, onan extension of shaft I21. This roller bears on a cam I32 which isrotatable on a stud shaft I33 attached to the side plate 3|.

2 in synchronism with the indexing mechanism by a gear I 34 attachedthereto, that is in mesh with the continuously rotating gear IN on thebushing I03 carrying the above-mentioned mutilated gear.

In the operation of this modification,.the gear 94 is first meshed withone of the gears 91, 98 or 99 to determine the speed at which the discsI05 and I06 and gear IOI are to rotate, and, therefore, the time betweeneach impression and each indexing operation. Next the discs I05 and I06are rotated relative to each other so that the proper number of pins IIImay be inserted in the slots thereof. When this has been done, theinstrument is started, and periodically the low portion of cam I32 willcome under roller I3I to lower the print wheel 54 and thereby make animpression on the chart. Immediately after this, the low portion of thecam formed by discs I05 and I06 will come under roller I I 5 of thelocking member II3 so that its lower end may be moved away from wheelH2, and pins III engage the teeth thereof to rotate shaft 82. Thisrotates shaft 85 to connect another thermocouple in circuit with thegalvanometer and also, through gearing 86, rotates shaft II5 to bringanother character 55 on the print wheel 54 into printing position. Apredetermined time thereafter, the low portion of cam I32 again comesunder roller I 3| to cause an impression to be made on the chart, and anew cycle is started.

If, for example, sixteen records are to be made, a thermocouple switchwith enough terminals for that many thermocouples will be provided, anda print wheel with sixteen characters will be provided. Then enough pinsIII will be inserted between discs I05 and I06 to turn the wheel H2one-sixteenth of a revolution upon the occurrence of each indexingmovement. By inserting twice as many pins III in the discs, the wheel II2 will make one-eighth of a revolution each time, and eight records willbe obtained. A new print wheel with only eight characters will be placedon shaft I27 in such a case. In this modification, the print wheel ischanged by moving shaft I 21 laterally away from shaft II5 to releasethe spring fingers I29 from bushings I30. The slots I2I in member I20permit this to be done and also properly locate the shaft I 21 uponreplacement. To remove the print wheel 54 from shaft I21, the left-handarm I28 is first removed, and the print wheel in then slipped oil. theend of the shaft.

In Fig. 13, there is shown a modified form of drive from shaft 82 toshaft 32 or II5. There is disclosed here the use of bevel gears I35 andshaft I36 upon which they are mounted, instead of the spur gearing 86 ofFig. "I. These gears can be interchangeable, and it is a matter ofpreference which is used.

In Figures 14 and 15, there is shown an alternative form of ink wheel.Instead of using the interchangeable cup 60 and felt BI, this ink wheelI31 is provided with a series of angular cups I38 into which are tightlyfitted holders I39 for felt ink pads I40. Each of the holders isprovided with a slot I in its bottom for communication between the inkreservoir at the bottom of cup I 38 and the felt pad I40. In order toreplenish the ink supply of this type, the ink wheel is removed andturned on its side, after which a screw plug I42 is removed to giveaccess to the reservoir. The ink can best be inserted by the use of adropper.

Each of the above-described embodiments of the invention is designed tohave a predetermined number of cycles of the instrument occur betweeneach printing operation. Thus, the, time interval between printing orrecording operations is fixed regardless of the length of time requiredfor balance of the instrument to its new value following a change fromone I thermocouple to another. For example, if the I time allotment foreach recording operation is I sufliciently large to permit theinstrument to I balance at a new value after balancing for a valuewidely separated from the new value, the objectionably large for timeallotment may be balancing to a value not widely different from the,preceding value. Ordinarily it is desirable to record value after valueas rapidly as the balancing operations will permit. If, on the otherhand, the time allotment to each record is fixed and is small, theinstrument may not have time to balance to the new value before therecord is made. It follows therefore that for service in which thevalues are not widely separated, the fixed time cycle of printing ispermissible, but for service in which some of the values are widelyseparated and others are close together, the time allotment is desirablyonly that required for balance. Such an arrangement will now bedescribed, the same reference numerals being used for the same parts. Itis to be understood in the following description that the printingmechanism may be either of the type disclosed in Figs. 2-4, or the typeof Fig. 9. The printing per se is the same, but the manner of rotatingthe.cams I0 and, II which control the printing and indexing operationsdiffers from that of the previous embodiments.

The manner of obtaining the variable time between operations is bycontrolling the rotation of the cams I0 and 1| in accordance with theposition of lever I6, which lever moves variable and smaller amounts asthe measuring mechanism nears a balanced condition. The counterclockwisemovement of lever I6 (Fig. 16), and therefore the adjustment of shaft 22and contact -20, is regulated by which of the steps on arm I 6G engagesprojection I4" on secondary pointer I4. As the galvanometer approachesbalance during the cycles of the instrument, the projection I 4', willbe positioned nearer and nearer to a position in which it will lie inthe path of step I6G', and at that time the instrument is in balance andthe carriage 23 is properly positioned to print.

In order to utilize the movement of lever I6 to regulate the printing,the lever 8 is provided with an arm 8A whose lower surface is formed asan arc which is concentric with shaft IGB when the roller 83 rests onthat portion of cam II, as is shown in Fig. 16. The arm 8A is adapted toengage and be stopped by a pin I 6H, extending back of lever I6, duringeach cycle that the projection I4 is far enough from its balancedposition to engage any step beyond either of the steps I6J on the armIGG as is shown by the dotted line position. The engagement between arm8A and pin I6H limits the clockwise movement of lever 8. When, however,the mechanism is near enough balanced so that projection I4" is engagedby one of the steps I6J, the pin'ISH will be beyond the end of arm 8A,and lever 8 can move further clockwise. Sometime within the next fourcycles of the instrument after projection I4" has been engaged by stepIN, the instrument will be in balance, and the step IGG' will engage theprojection I4" and it will be safe to print.

' The ratchet wheel so in this embodiment of the invention is made withonly eight teeth, instead of a larger numberas previously described, andeach stroke of lever Bdssufllcient to move it only the distance of onetooth. During the time that pin ISH is in the path of armBA, the link 64and plate 65 can move the pawl 6] through an are that is slightlysmaller than the distance: between two teeth on. ratchet 88. But whenprojection W'is engaged by step IBJ, the

' lever I6 is stopped with pin IGH out of the path of arm 8A, andcontinued rotation of cam I'I, formed in this case with a cut-outportioii IIA, will bring the portion I IA under roller 83 ahd permitlever 8 to rotate clockwise far enough for pawl 61 to engage the nexttooth on ratchet 68. counterclockwise movement of lever 8 will thencause'pawl 61 to rotate wheel68 the distance 01 one tooth. Such rotationof the wheel 68 continues until the instrument is in balance, and theprinting and indexing operations have taken place.

The cam 10 is in this used to prevent accidental movement of the wheelI8.

From the above description, it. will be apparent that four cycles of theinstrument after it has come near enough in balance for projection I4"to be in'the path of one of the steps IU of arm ISG, a printingoperation will take place. Since the instrument is designed so that itwill come into balance by the time this fourth cycle occurs,

it is possible to print justas the galvanometer pointer reaches its nullposition. Immediately case formed with two cut-out portions, and thecams III and 'II are prothe step IGG' before movement of ratchet II isinitiated.

By making the circuit changing and printing operations effective'uponmovement of ratchet 88 for a distance of only one, two, or three teeth,the eflect of speeding up the printing may be attained. Under someconditions, the arrangement by which ratchet 88 isoperated from a singlemechanical balance operation (following any contact of HQ with I4"), andthe printing an circuit changing is performed from a single movement ofratchet 88, is undesirable, especially in an industrial plant where theinstrument is subjected to vibration, and accidental mechanical balancemay occur without true electrical bal- -ance of the system. In a form ofthe invention described hereinafter with reference to Fig 17, a singlebalance stroke arrangement is shown.

It the value of the temperature of one of the thermocouples is higher orlower than the range for which the chart was designed, the instrumentwill move the print wheel carriage to one end of thereafter theinstrument is connected to another thermocouple, and a new measurementis made. If the value of the new measurement is near the value of theone just made, it is possible that the instrument will print'again afterfour cycles. If, however, the new measurement'has a value of substantialdifference from the previous one, it will take a longer time for theinstrument to reach a balanced position, but the printing will occur assoon as the instrument comes into balance. Thus, there is no time lostbetween making records of the values of the temperature to which thevarious thermocouples are 7 subjected.

Although, as shown, four cycles are required for the printing operationto take place after the projection I4" has engaged step I6J, it will beapparent that other arrangements may be made without departing from thespirit of the invention. For example, if the arm 8A is lengthened, orthe pin IGH moved to the left, the operation of ratchet 68 may be madedependent upon the" attainmentof a condition closer to balance, or, ifdesired, upon complete balance. To'this end, additional holes I 6K areprovided in lever I6 into its travel. Thereafter, the pawls IE or IBFwill be unable to turn gear I8 as they engage it, so the lever I8 cannotmove from its extreme clockwise direction as determined by cam II.There-- fore, 'pin- IBH will be out of the path of arm 8A, and printingwill occur in the usual manner.

Such an arrangement will permit the instrument to then continue torecord the value of the other thermocouples, irrespective of whether oneor more of them is momentarily too high or too low for itsvtrue' recordto be made on the chart. The.

appearance of one of the record marks on an edge of the chart is anindication to the operator that its value is incorrect, and thecondition 0 of which it is a record should be rectified.

There is disclosed in Fig. 1'! another embodiment of the invention inwhich printing occurs at irregular intervals, depending upon the time ittakes the measuring mechanism to become balanced. This embodimentdiflfer from that of Fig. 16 in that the printing and indexingoperations take place during the cycle immediately following that inwhich the instrument reaches a state of balance, and the operations aredirectly related to the rotation of the helically threaded shaft 22 uponwhich the printing carriage 2; is

mounted.

' As has been stated above, the pawls ICE and QIBF rotate gear I8 and,by means of another smaller gear on -it, shaft 22 an amount proportionalto the deviation of the galvanometer point-e the characters above thecorrect point along er 2. from its null psition. Each cycle of theinstrument, the shaft 22 is-therefore rotated some amount until theinstrument is in balance, and the shaft remains in its then positionwith the chart. i

In order to utilize the shaft 22' to control the I printing, a memberI43 having a generally triangularly shaped opening I in its lower end isfrictionally mounted upon one end of the shaft.

- The opening I in member I43 is provldedfalong its upper end with twoshoulders I45 separated by a notch I46 and. at its lower end with asecond notch I". Extendinginto the opening is which the pin IGH may be'inserted if it is desired to wait until the instrument is nearer balancebefore the printing operation is initiated. In such a case, theprojection I4" would engage either the step between" step I'IiJ and HG,or

a pin I48 on an arm formed on the oscillating lever 8. As lever 8 isrotated in a counterclockwise directiori by cam II, the pin I will moveinto notch I" and position the member I ma definite relation thereto. 1Thereafter-as lever 1 II moves clockwise, the pwhi I48 will rise-in theopening and engage. either oneoi' the shoulders I" or the notch I,depending whether because of its frictional fit thereon, the member I43will have moved from the position it took when pin I48 was in notch I41to its dotted line position if shaft 22 was rotated clockwise. If suchis the case, pin I48 will engage one of the shoulders I45; if, however,the instrument was in balance, the member I43 will not have moved, andpin I48 will enter notch I46, thus allowing lever 8 to take its fullclockwise stroke.

During the time that lever 8 is oscillating when the instrument is notin balance, the link 64 and pawl plate 65, oscillate through an are thatmoves pawl 61 a distance slightly less than the distance between twoteeth of the rachet 68, and that ratchet and the cam I attached theretoare not rotated. The cycle after the instrument reaches balance,however, there will be no movement of the shaft 22 and member I43, soupon' its upstroke pin I48 will enter notch I46 and thus permit lever 8and plate 65 to move clockwise enough for pawl 61 to engage the nexttooth on ratchet 68. On its counter-clockwise movement, the pawl willthen move the ratchet for a distance of one tooth, which, in this case,is one-eighth of a revolution.

It will be noted that in this embodiment of the invention, the cam I0 isformed with eight cut-out portions 70A, and there are eight pins I1between the cams III and II. Therefore, each time the ratchet 68 and camIII are moved, a printing and indexing operation will take place.

Although it is not shown in this embodiment of the invention, it isobvious that a locking pawl of the type shown at IS in Fig. 5 may beused to prevent accidental turning of the indexing wheel I8.

From the above description, it will be seen that I have devised arecording mechanism for a multiple potentiometer that can be actuated invarious ways, thus making such an instrument versatile enough forvarious types of installations.

While in accordance with the provisions of the statutes, I haveillustrated and described the best form of my invention now known to me,it will be apparent to those skilled in the art that changes may be madein the form of the apparatus disclosed without departing from the spiritof my invention as set forth in the appended claims, and that certainfeatures of my invention may sometimes be used to advantage without acorresponding use of other features.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. In a recording mechanism having a chart adapted to receive recordmarks, a print wheel having printing characters thereon, means to bringone of said characters into engagement with said chart, anintermittently rotated cam controlling said means, a ratchet connectedto said cam, a pawl to rotate said ratchet, an oscillating lever, drivemeans between said lever and pawl, means to oscillate said lever wherebysaid cam will be rotated to permit a printing operation to take placeand means to vary the connection between said lever and oscillatingmeans to change the speed of rotation of said cam.

2. In a measuring instrument the combination of a print wheel, means torotate said print wheel comprising a shaft, drive means between saidshaft and print wheel and drive means for said shaft comprising atoothed wheel, locking means therefor, a rotatable member having a pinthereon adapted to successively engage the teeth of the toothed wheel torotate the same toothed wheel, a cam moving with said member adapted tocontrol the locking means, rotating means for said member, and means tovary the time required for each rotation of said member by said rotating'means.

3. In a measuring instrument the combination of a chart support, a printwheel adapted to be periodically brought into engagement with a chart onsaid support and then rotated a portion of a turn, means to move saidprint wheel into engagement with a chart on said support, means torotate said print wheel, means to synchronize the-operation of saidfirst mentioned two means, locking mechanism controlled by saidsynchronizing means to prevent rotation of said print wheel atpredetermined times, means to intermittently operate said moving meansand said rotating means and means to vary the time interval between theoperation of said rotating and moving means by said operating means.

4. In a measuring instrument having a chart, a carriage including a, U-shaped member, means to support said carriage in a position adjacentsaid chart for movement laterally of the chart comprising a guide memberand a shaft, a bearing in the U-shaped portion of said carriage, saidbearing surrounding said shaft, a support tiltably carried by saidcarriage and mounted e,

for tilting movement on said bearing, a print wheel and an ink padtherefor carried by said support, and means to tilt said support insaidcarriage around said bearing to bring said print wheel into contact'withthe chart 5. In a measuring instrument, a carriage including a U-shapedmember, means to support said carriage including a parallel support andshaft, 3, bearing in the U-shaped member and received by said shaft,means to move said carriage along said support and shaft to a positioncorrespondingto the value of a measurable condition, a support mountedon said bearing for movement relative to said carriage whereby thesupport may move along the first support and shaft with the carriage andmay move around the bearing relative to the carriage, a print wheelhaving a plurality of characters and an ink wheel having an ink pad foreach character, both rotatably mounted on relatively stationary axes onsaid support, and means acting through said bearing to rotate said inkwheel and print wheel to bring said character into engagement with saidink pads.

6, In a measuring instrument, a shaft, a bearing slidable along saidshaft, a carriage including a U-shaped member having the sides of the Usurrounding the ends of the bearing, a support movably mounted on saidbearing between the sides of the U-shaped member, means located betweensaid support and one side of said L'- shaped member to maintain aconstant {tension aaginst movement of said support on said carriage,means to shift said carriage and bearing on said shaft, and means tomove said support on said carriage.

7. In a measuring instrument adapted to sequentially record a pluralityof values on a chart, recording means comprising a rotatable recordingmember, means operative to rotate said recording member including atoothed wheel, in termittently operated rotating means periodicallyoperative to rotate said toothed wheel a predetermined amount, a cammember rotatable with said rotating means, a locking member acting tomaintain said toothed wheel in a fixed position, said cam operating tohold said locking member in its operative position, said cam beingpositioned with respect to said rotating means so that the cam willrelease the locking means just prior to the time the toothed wheel isrotated.

8. In a measuring instrument having a print wheel and gearing forrotating same, the comloination of means to rotate said gearingcomprising a cam having a member attached thereto, means tointermittently rotate said cam and member, a toothed wheel engaged bysaid memher as it rotates, said toothed wheel serving to drive thegearing, a locking member for said toothed wheel operated by said cam tonormally prevent rotation of said toothed wheel and gearing, said camand pin being so related to each other that the cam will release thelook just as the member rotates the toothed wheel.

9. A recording instrument having a chart adapted to receive recordsthereon, the combination of a print wheel carriage mounted for movementacross the chart, a print wheel in said carriage, means to move saidprint wheel from a position in which it is out of engagement with thechart to a position in which it engages the chart including a camfollower operatively connected to said print wheel for movementtherewith, means to bias said print wheel and cam follower for movement,in a direction to bring said print wheel into engagement with saidchart, a cam engaged by said cam follower serving at times to inhibitthe movement of said cam follower, means to rotate srcl cam including aratchet fastened to said cam, a pawl engaging said ratchet, anoscillating lever upon which said pawl is mounted, means to periodicallyoscillate said lever and means lation imparted to said lever.

COLEMAN B. MOORE.

to vary the amount of oscil-

